How to detect if machine is joined to domain (in C#)?

Question

How do I detect whether the machine is joined to an Active Directory domain (versus in Workgroup mode)?

Answer 1

ManagementObject cs;
        using(cs = new ManagementObject("Win32_ComputerSystem.Name='" + System.Environment.MachineName + "'" ))
        {
            cs.Get();
            Console.WriteLine("{0}",cs["domain"].ToString());
        }

That should allow you to get the domain. I believe it will be null or empty if you are part of a workgroup and not a domain.

Make sure to reference System.Management

Answer 2

You can PInvoke to Win32 API's such as NetGetDcName which will return a null/empty string for a non domain-joined machine.

Even better is NetGetJoinInformation which will tell you explicitly if a machine is unjoined, in a workgroup or in a domain.

---

Edit: Using NetGetJoinInformation I just put together this, which worked for me:

public class Test
{
    public static bool IsInDomain()
    {
        Win32.NetJoinStatus status = Win32.NetJoinStatus.NetSetupUnknownStatus;
        IntPtr pDomain = IntPtr.Zero;
        int result = Win32.NetGetJoinInformation(null, out pDomain, out status);
        if (pDomain != IntPtr.Zero)
        {
            NetApiBufferFree(pDomain);
        }
        if (result == Win32.ErrorSuccess)
        {
            if (status == Win32.NetJoinStatus.NetSetupDomainName)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        else
        {
            throw new Exception("Domain Info Get Failed");
        }
    }
}
internal class Win32
{
    public const int ErrorSuccess = 0;

    [DllImport("Netapi32.dll", CharSet=CharSet.Unicode, SetLastError=true)]
    public static extern int NetGetJoinInformation(string server, out IntPtr domain, out NetJoinStatus status);

    [DllImport("Netapi32.dll")]
    public static extern int NetApiBufferFree(IntPtr Buffer);

    public enum NetJoinStatus
    {
        NetSetupUnknownStatus = 0,
        NetSetupUnjoined,
        NetSetupWorkgroupName,
        NetSetupDomainName
    }

}

Answer 3

The Environment variables could work for you.

Environment.UserDomainName

MSDN Link for some more details.

Environment.GetEnvironmentVariable("USERDNSDOMAIN")

I'm not sure this environment variable exists without being in a domain.

Correct me if I'm wrong Windows Admin geeks -- I believe a computer can be in several domains so it may be more important to know what domain, if any, you are in instead of it being in any domain.

Answer 4

Don't fool with pinvoke if you don't have to.

Reference System.DirectoryServices.Activedirectory, then call:

System.DirectoryServices.ActiveDirectory.Domain.GetComputerDomain()

Throws an ActiveDirectoryObjectNotFoundException if the machine is not domain-joined. The Domain object that's returned contains the Name property you're looking for.